During high-level Pentagon meetings, acting US Defence Secretary Patrick Shanahan harshly criticised Lockheed Martin's F-35 fifth-generation fighter jet programme, using an expletive to describe the fighter, an ex-Defence Department official was quoted by Politico as saying.
According to the former official, Shanahan called the warplane "f***ed up", claiming that Lockheed "doesn't know how to run a programme" and that "if it had gone to Boeing, it would be done much better".
Politico also cited a former Trump administration official as saying that when Shanahan was Deputy Defense Department chief, he had repeatedly "dumped on" the F-35 programme, slamming it as "unsustainable".
"The cost, the out-years, it's just too expensive, we're not gonna be able to sustain it", Shanahan allegedly pointed out at the time.
The F-35 is known to be the most expensive aircraft programme in history, with a projected lifetime cycle total cost of $1.5 trillion.
The last few years have seen the F-35 programme face a whole array of costly setbacks and technical delays.
In September, a Marine F-35B crashed in South Carolina due to technical failure in a jet engine fuel pipe, according to investigators.
In 2016, the US Air Force ordered the grounding of 15 F-35A jets after the discovery of "peeling and crumbling" coolant tube insulation installed in the wings of the jet.